Closed carriers for sewage and the like are subject to various kinds of damage. Obstruction by plant roots is one which occurs when such a carrier leaks and the moisture attracts the roots. Damage may also occur because of shifting or settling of the earth surrounding the carrier or of structures to which the carrier is connected. Indeed damage can arise from causes as various as the vagaries of nature, and regardless of cause, the damage may require repair.
One well known technique for repairing a damaged closed carrier such as a sewer line is to clear the line using any of a variety of snakes, jets, robots or other well known equipment. After the carrier is clear it is lined with a fluid impermeable liner. Lining has been accomplished by pulling a fabric liner saturated with a curable resin into the carrier, inflating a bladder inside the liner to press the liner against the inside of the carrier while the resin cures and then removing the bladder. Various remote control machines are available to trim and grind the ends of such a liner to assure uninterrupted flow through the carrier. This lining method has worked well in some circumstances, as it leaves a thin, chemical resistant, smooth and impenetrable liner inside the carrier.
One difficulty with this prior art lining technique is that heretofore it has not been possible to line a portion of a carrier that was not easily accessible at both ends. Access to one end of a carrier has been required to feed in the resin-saturated liner, and access to the opposite end has been required for pulling a cable attached to the liner to place the liner properly inside the carrier before inflating it. This requirement for access has precluded using the lining technique described on branch or lateral carriers which connect to a main carrier without a manhole or other service access at the connection. Such "blind" connections are typical of, e.g., the connection of a sewer line from a residence to a municipal sewer main line, typically found under or adjacent the street in front of the residence. In making a residential sewer connection, it is typical to use a T fitting to join the residential line of between 4 inches and 8 inches in (internal) diameter with the sewer main. The sewer main may be 12, 16, 18 or more inches in (internal) diameter, but the sewer main is usually too small to permit a worker direct access to the interior of the lateral connection. Generally in such a connection the axis of the branch line is perpendicular to the axis of the main, although connections at other angles such as 45.degree. Ys are also used on occasion. Thus a connection is "blind" or inaccessible where it is not feasible to get a worker at the connection by moving through one of the carriers that forms the connection.
Heretofore liners have not been pulled into a lateral line through such a blind connection. Friction where the cable must bend around the connection from the lateral line to the main damages the cable itself, and excessive force on the cable has been necessary. Therefore, the lining technique described has not been available for a great many applications for which it would otherwise be suited, and resort has often been had to excavation of the entire line to make a repair. Excavation not only is more expensive than lining, but also it disrupts landscaping, sidewalks and other intervening structures.